Here's one I enjoy. It's by OLL1E. This is an excerpt of his arousing story .
Slave Girls From Earth – Yvette. By OLL1E.
Yvette is punished again by the Herrunderrai guardettes.
This time, however, she found herself in a different part of the punishment block, in a circular stone room with some sort of metal framework set into the floor in the middle. The guardettes dragged her over to the frame attaching her to it by short chains on her wrists and ankles, so she was leaning back slightly, her arms stretched upwards and outwards, legs bent back at the knee, her feet off the ground, thighs spread wide. A guardette pulled various levers on a control panel that stretched her body taut while two others ran their leather-gloved hands over her naked body, occasionally slapping her face and breasts, and pulling her pubic hair. Then one of them began to beat her with a multi-tailed whip, lashing her breasts, belly and thighs.
“That’s just to warm you up, slut,” rasped a guardette. “You’ll soon see what this device is all about!”
After delivering a few more lashes, they stood watching, as the guardette behind the control panel began to turn dials and pull more levers. Yvette suddenly felt like she was being pulled apart by red hot pincers, screaming at the same time, she felt that she was being drowned, crushed and strangled. She was soon soaked in sweat which ran in rivulets over her dirt-streaked skin and dripped into her eyes from her bedraggled hair.
“How do you like this device, Earth creature? It’s called the excruciator! It can inflict many types of pain and discomfort on you all at the same time! Without leaving any marks on your vermin body!”
“Nyyaaaaaaaghhhhhhhhhh….grrrrssssssssggghhhh….raaaaaarrrrggghhhhhhh!”
“I think the little wretch likes it! Increase the pain levels! But make sure she doesn’t faint!”
“Nnnrrrrrrrggggghhhhhhphssslllrrrrgll! Rrrrrrgggghhhhyiieeeeeeeeekkkk!”
“Well, slave, now we’re going to have a writhing contest, to see which slave can writhe the most on these devices! There is another slave on an identical device next door! The winner of our contest gets one day off from working in the mines, but the loser goes back on the excruciator, until they learn to writhe better!”